This invention relates to the measurement of physical characteristics of three dimensional (3D) objects such as turbine blades used in aircraft engines and the like, and more particularly, to a method for checking the alignment of a structured light 3D measurement system employed in such testing using line video data and interferometry tools.
In testing of objects such as turbine blades which have a complex outer surface or contour, it is advantageous to employ a light gauging testing methodology rather than using conventional hard gauging techniques. This involves the use of a structured light system such as the 4DI light system available from Intelligent Automation. To obtain the most accurate test data for evaluating a part to determine its acceptability, the structured light system employed must be properly setup and aligned. Minor variations in the width of lines of light projected by the structured light system onto the object, for example, can significantly effect the test results and cause an otherwise acceptable part to be rejected, or an unacceptable part to be approved. Similar problems occur if optical windows within the system are not properly aligned.
Previously, alignment of the structured light system to a part under test was accomplished manually by a technician, with the technician visually determining when alignment was proper. The present invention is directed to a test setup methodology by which optical windows are checked to determine when optical windows are correctly aligned. The lines projected by the structured light system are also tested to insure that they are consistent and fall within the specifications necessary to obtain valid test data.